Merge AudioRendererImpl and AudioRendererBase; add NullAudioSink

content/renderer/media/renderer_webaudiodevice_impl.cc

Index: content/renderer/media/renderer_webaudiodevice_impl.cc
diff --git a/content/renderer/media/renderer_webaudiodevice_impl.cc b/content/renderer/media/renderer_webaudiodevice_impl.cc
index 2a90144bce0e9398e68d3eea24f15bb22bb12d06..07ea9c2c6e4e071b01c1b36635760d47bdabf285 100644
--- a/content/renderer/media/renderer_webaudiodevice_impl.cc
+++ b/content/renderer/media/renderer_webaudiodevice_impl.cc
@@ -37,9 +37,9 @@ double RendererWebAudioDeviceImpl::sampleRate() {
   return 44100.0;
 }
 
-size_t RendererWebAudioDeviceImpl::Render(const std::vector<float*>& audio_data,
-                                          size_t number_of_frames,
-                                          size_t audio_delay_milliseconds) {
+int RendererWebAudioDeviceImpl::Render(const std::vector<float*>& audio_data,
+                                       int number_of_frames,
+                                       int audio_delay_milliseconds) {
   // Make the client callback to get rendered audio.
   DCHECK(client_callback_);
   if (client_callback_) {